Rain pants, also called rain trousers, are waterproof or water-resistant pants

Trousers

Trousers are an item of clothing worn on the lower part of the body from the waist to the ankles, covering both legs separately...

 worn to protect the body from rain

Rain

Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

. Rain pants may be combined with a rain jacket to make a rain suit. Rain gaiters

Gaiters

Gaiters are garments worn over the shoe and lower pant leg, and used primarily as personal protective equipment; similar garments used primarily for display are spats....

 may also be used for further protection.

While rain pants can be made of plastic or coated nylon, modern waterproof materials are commonly used, including waterproof-breathable fabric

Waterproof fabric

Waterproof fabrics are fabrics that are inherently, or have been treated to become, resistant to penetration by water and wetting. They are usually natural or synthetic fabrics that are laminated to or coated with a waterproofing material such as rubber, polyvinyl chloride , polyurethane , silicone...

 such as Gore-Tex

Gore-Tex

Gore-Tex is a waterproof/breathable fabric, and a registered trademark of W. L. Gore and Associates. It was co-invented by Wilbert L. Gore, Rowena Taylor, and Gore's son, Robert W. Gore. Robert Gore was granted on April 27, 1976, for a porous form of polytetrafluoroethylene with a...

.